Typical robotic surgical gripping instruments or tools use wires or cables to open and close jaws of the tool. With the jaws closed around tissue, the wires or cables may be further tensioned to generate a gripping torque and apply a gripping force on the tissue. When the robotic surgical gripping instrument or tool was new, a predetermined position limit in a capstan or input disk is set in the tool. The predetermined position limit is not exceeded so that the wires or cables in the robotic surgical gripping instrument or tool are not overloaded.
However as the robotic surgical gripping instrument or tool and its cables are used over and over again after being re-sterilized, it ages and the wires or cables that open and close jaws of the tool may stretch or the instrument may compress causing slack in the wires or cables. With stretched cables or a compressed instrument limiting the position of the input disk to the predetermined position limit may not allow a maximum torque to be reached. This results in a reduced gripping torque at the jaws and a reduced gripping force being applied to tissue. This may be particularly problematic during robotic surgical procedures.
It is desirable to provide a maximum torque to the jaws of a robotic surgical gripping instrument or tool over its lifetime so that a maximum gripping force may be applied to tissue during robotic surgical procedures.